Wired pipe telemetry systems using a combination of electrical and magnetic principles to transmit data between a downhole location and the surface are described in, for example, U.S. Pat. Nos. 6,670,880 and 6,641,434. In these systems, inductive transducers are provided at the ends of wired pipes. The inductive transducers at the ends of each wired pipe are electrically connected by an electrical conductor running along the length of the wired pipe. Data transmission involves transmitting an electrical signal through an electrical conductor in a first wired pipe, converting the electrical signal to a magnetic field upon leaving the first wired pipe using an inductive transducer at an end of the first wired pipe, and converting the magnetic field back into an electrical signal upon entering a second wired pipe using an inductive transducer at an end of the second wired pipe. Several wired pipes are typically needed for data transmission between the downhole location and the surface. Before connecting a new wired pipe to existing wired pipes in a borehole, it is desirable to test that the new wired pipe can transmit a signal. After connecting a new wired to existing wired pipes in the borehole, it may also be desirable to test that the system can transmit a signal. An apparatus and a method for accomplishing such testing is desired.